Classifying – separating – and assorting solids – Sifting – Elements
Patent
1981-12-04
1986-01-07
Lutter, Frank W.
Classifying, separating, and assorting solids
Sifting
Elements
209397, B07B 146
Patent
active
045632707
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention refers to a screen panel for a vibratory screening machine.
Such a screen panel consists of at least one cast, injection-molded or vulcanized perforated panel of elastically flexible material, such as plastic or rubber, with a multitude of screen openings and crosspieces surrounding them which are connected with each other as one piece and form perforated panels.
Such screen panels are predominantly used for the classification of bulk materials. In order to avoid an obstruction of the screen openings, particularly by means of near-size material, it is known to take measures towards a self-cleaning effect for such screen panels. As a rule, the screen openings are designed with a conic expansion in the direction of the flow of the material to be screened so that wedged-in near-size material can be moved by being carried along by the material to be screened in its direction of flow. However, there exists also bulk material due to which the screen openings get choked up with mud and, in this instance, the individual particles depositing in the screen openings are by far smaller than the respective near-size material which makes the conicity of the screen openings ineffective against the choking-up with mud.
A known screen panel of the kind mentioned in the introduction is described in the German Disclosure Publication No. 27 01 307. In this instance, the self-cleaning effect is improved by the fact that elastic tongues are formed in the individual screen openings capable of their own vibration. Two screen holes are always connected with each other by a slot in this case and the strip formed in this way, which is only rigidly connected with the crosspieces on one end, has a higher elasticity in comparison with the edges of the screen openings and carries out relative movements. However, the self-cleaning effect caused in this fashion is essentially limited to the area of the freely vibrating ends of the tongues since, towards the connecting point with the crosspieces, the relative movement of the tongues is more and more reduced towards the edges of the screen openings.
A known screen panel is also described in the German Pat. No. 965,546. In this case, the screen panel consists of elastic, strip-shaped elements which have also strip-shaped tongues attached laterally in transverse direction which extend in a determined arrangement to the adjacent strip-shaped element and surround the screen openings. These tongues have no connection with the respective adjacent crosspieces and, therefore, can effect their own vibration and thus a relative movement at least in the area of their free ends towards the continuous crosspieces whereby a self-cleaning effect is obtained which is essentially limited to the area of the ends of the tongues in this case as well. Owing to the relative movements of the vibrating strips in comparison with the crosspieces to which they are attached, special difficulties are encountered, on the one hand, with regard to durability and, on the other hand, with respect to the trueness of the holes of the screen openings. For this reason, the tongues, being additionally capable of vibrating, are, at least partially, provided with a reinforcement and, furthermore, project downward beyond the actual sectional height in order to achieve a sufficient trueness of the mesh or hole with the larger movement in comparison with the more rigid crosspieces.
Wire screen panels have already been known for a long time in which the individual screen openings are surrounded by screen wires which consist of steel. In this case, relative movements of the individual screen wires are produced by means of a differing configuration of the screen wires next to each other or by means of differing wire thicknesses which cause a cleaning effect. The individual screen wires of differing bending resistance must be adjusted to each other in a special manner and fastened to a joint support frame. Even though such wire screen panels have been in use for already more than twenty years, t
REFERENCES:
patent: 2870910 (1959-01-01), Wehner
patent: 3194397 (1965-07-01), Taege
patent: 4120785 (1978-10-01), Kandmori et al.
patent: 4222865 (1980-09-01), Valeri
patent: 4347129 (1982-08-01), Rutherford
"Screen Panels and Their Use" Aufbereitungstecknik, Year 1, (1960), Issue 11, pp. 457-473 and Issue 12 pp. 501-508.
Bond Wm.
Lutter Frank W.
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